Port forwarding broken

Port forwarding works if the START and END port are the same but broken if they are different. The premise of START (EXTERNAL) port and END (INTERNAL) port is if i get a request on 443 for ssl and have it set up on something on my internal network on a diff port (hass.io) 8123 than port forwarding with a start port of 443 and end port of 8123 would do this; but the router web UI errors out when trying to set this rule!!!!! Shaw please fix this web UI bug, this is important for some people!

I need 443 specifically for let's encrypt certs for my home automation stuff. The router has predefined ports in a drop down menu for port forwarding and 443 is one of them. The web Gui works as long as you don't try and forward any of shaw's predefined ports.